Synthesis of Janus Transition Metal Dichalcogenides by Plasma-assisted Selenization Process for Wafer-scale Production

Paul Albert Sino^1*, Lee Ling², Sumayah Wani², Chieh-Ting Chen², Mingjin Liu^1,2,5, Yao-Zen Kuo², Bushra Reman², Feng-Chuan Chuang^1,3,4, Yu-Lun Chueh^1,2,5

¹Department of Physics, National Sun Yat-sen University, Kaohsiung City, Taiwan
²Department of Materials Science and Engineering, National Tsing-Hua University, Hsinchu City, Taiwan
³Physics Division, National Center for Theoretical Science, Hsinchu City, Taiwan
⁴Department of Physics, National Tsing-Hua University, Hsinchu City, Taiwan
⁵Frontier Research Center on Fundamental and Applied Sciences of Matters, National Tsing-Hua University, Hsinchu City, Taiwan

* Presenter:Paul Albert Sino, email:plsino@g-mail.nsysu.edu.tw

Materials exhibiting asymmetric structure like Janus Transition Metal Dichalcogenides (TMDs) have sparked research interest in recent years due to their unique properties which are highly desirable for various applications such as piezoelectronics, electrocatalysis, hydrogen evolution reaction (HER), and sensing, among others. However, the experimental research on Janus TMDs is not mature and the synthesis of wafer-scale size is yet to be reported. Here, were present, for the first time, the synthesis of wafer-scale (WS) Janus MoSSe by plasma-assisted selenization process (PASP). Initially, we grow WS monolayer MoS₂ on 2 in. sapphire by oxygen-assisted chemical vapor deposition (OACVD) process. By carefully controlling the kinetics parameters such as temperature and plasma power, we are able to transform the WS MoS₂ to Janus MoSSe. Specifically, we substituted the top S of MoS₂ with Se by controlled selenization process coupled with plasma. A set of microscopies and spectroscopies have confirmed the successful synthesis of WS Janus MoSSe and its excellent wafer-scale uniformity. We further demonstrated the universality of PASP by growing Janus WSSe flakes. Our method provides an avenue for wafer-scale production and full exploration of Janus TMDs towards novel electronic applications.

Keywords: Wafer-scale Production, Janus MoSSe, Janus TMDs, Janus WSSe